JP4079503B2 - Analytical electron microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of an analytical electron microscope having both the function of an electron microscope and the function of a fluorescent X-ray analyzer.
[0002]
[Prior art]
Conventionally, analyzers that perform elemental analysis of minute portions of a sample have been developed. Examples of such apparatuses include an apparatus in which an X-ray detector is attached to an electron microscope, and a fluorescent X-ray analyzer.
[0003]
An apparatus with an X-ray detector attached to an electron microscope accelerates an electron beam emitted from an electron gun and irradiates the sample so as to focus on the surface, thereby generating characteristic X-rays from the sample. Characteristic X-rays are detected by an X-ray detector. The X-ray energy is measured by an X-ray analyzer to analyze the types and amounts of elements constituting the sample.
[0004]
By the way, when performing an elemental analysis of a sample with an apparatus in which an X-ray detector is attached to an electron microscope, there are the following problems. That is, in this apparatus, since the sample chamber must be evacuated, a sample having a high vapor pressure cannot be analyzed. In addition, since the irradiation position fluctuates due to charging of the sample by electrons and the irradiation current becomes unstable, the insulator cannot be analyzed as it is. Furthermore, since the vacuum residual gas component is baked on the sample surface by the electron beam irradiation, the sample is contaminated. Furthermore, since the background by the bremsstrahlung X-ray is large, the detection limit is worse than that of the fluorescent X-ray analyzer.
[0005]
Therefore, an X-ray fluorescence analyzer that eliminates the problems associated with an X-ray detector attached to an electron microscope has been conventionally developed. This fluorescent X-ray analyzer irradiates a sample with X-rays emitted from a microfocus X-ray tube, generates characteristic X-rays from the sample, and spectroscopically measures the characteristic X-rays. .
[0006]
[Problems to be solved by the invention]
However, when performing elemental analysis of a sample with a fluorescent X-ray analyzer, there are the following problems. That is, since a microfocus X-ray tube is used, it is difficult to obtain an extremely thin beam with high brightness. This is because, in order to perform elemental analysis at a microscopic part, the X-ray is required to be an extremely thin beam with a high brightness with a focal diameter of about 1 to 10 μφ. This is because the focal diameter of the X-ray is about 100 μφ. Therefore, conventionally, an ultrafine X-ray beam is formed by restricting X-rays from a microfocus X-ray tube with an orifice. However, with such an restriction with an orifice, the utilization efficiency of X-rays is reduced. It will be very bad.
[0007]
Further, the excitation efficiency of the low energy X-rays becomes extremely low due to the absorption of the low energy component contained in the primary X-rays by the tube window material. That is, the analysis accuracy of light elements decreases.
[0008]
In addition to preparing two electron microscopes and a fluorescent X-ray analyzer for analysis, the electron microscope and fluorescent X-ray analyzer must be used separately according to the analysis object and purpose. Is troublesome.
[0009]
The present invention has been made in view of such circumstances, and its purpose is to set the mode of the electron microscope and the mode of the fluorescent X-ray analyzer with a single unit, and select these modes according to the analysis object and purpose. By switching, it is possible to provide an analytical electron microscope that enables analysis under optimum conditions and that can form an ultrafine X-ray beam without lowering the X-ray utilization efficiency when the fluorescent X-ray analyzer mode is set.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that an electron gun that emits an electron beam, a lens that converges the electron beam, and a central axis of the electron gun below the lens are provided in a casing. And an electron microscope comprising an X-ray detector for detecting X-rays generated from the sample in the casing, wherein the lens and the sample support are provided. A target is movably disposed between a use position on the central axis and a non-use position deviating from the central axis, and when the target is set at the use position, the electron The X-ray generated from the target irradiates the sample when the focal point of the line is focused on the surface of the target, and the X-ray detector detects the fluorescent X-ray generated from the sample with the X-ray detector. When the mode and the target are set at the non-use position, the electron beam is focused on the surface of the sample, and the X-ray detector detects the characteristic X-rays generated from the sample. The microscope mode is set, and the target is airtightly fixed and supported by a support member provided movably on the casing, and the target and the support member are positioned when the target is in a use position. an electron beam generating section side to the sample side hermetically blocked, and as characterized and Turkey through communication between said electron beam generating section side sample side when brought into position the target at the non-use position in Yes.
[0011]
Further, the invention of claim 2 is characterized in that a collimator for limiting X-rays is disposed on the central axis side closer to the sample support part than the use position of the target.
[0013]
[Action]
In the analytical electron microscope of the invention of claim 1 having such a configuration, the fluorescent X-ray analyzer mode is set by setting the target at the use position. As a result, the analytical electron microscope exhibits the same function as a conventional fluorescent X-ray analyzer that measures a minute portion of a sample. Also, the electron microscope mode is set by setting the target to the non-use position. As a result, the analytical electron microscope exhibits the same function as the conventional electron microscope. In other words, a single analytical electron microscope is a device that combines the functions of an electron microscope and the function of a fluorescent X-ray analyzer. By switching these two functions depending on the analysis target and purpose, analysis under optimum conditions is possible. Is possible.
[0014]
In addition, when the support member that fixes and supports the target positions the target at the use position, the electron beam generation unit side and the sample side are hermetically shut off. Therefore, it is possible to make the sample side into the atmosphere or helium atmosphere while keeping the electron beam generating part side in a high vacuum.
[0015]
In particular, in the invention of claim 2, since the X-rays irradiating the sample are limited by the collimator, it is possible to easily obtain a high-intensity micro focus of X-rays. Therefore, since the X-ray beam from the target becomes extremely thin, the utilization efficiency of X-rays is extremely higher than that of the X-ray tube in the conventional fluorescent X-ray analyzer, and a highly sensitive analysis is performed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing an example of an embodiment of an analytical electron microscope according to the present invention.
[0017]
As shown in FIG. 1, the analytical electron microscope 1 of this example is configured by attaching an X-ray detector 3 to a scanning electron microscope 2 in the same manner as a conventional analytical electron microscope. The scanning electron microscope is conventionally known and includes an electron gun 5, an anode 6, a condenser lens 7 and an objective lens 8 in a casing 4. Further, the analytical electron microscope 1 is disposed between a target 10 made of a metal thin film disposed between the objective lens 8 and a sample support portion 9 a that supports the sample 9, and the target 10 and the sample 9. And a collimator 11 for limiting X-rays.
[0018]
As shown in FIG. 2, the target 10 is airtightly supported and fixed to the support member 12. The support member 12 is provided on the lower surface of the intermediate horizontal floor portion 4a of the casing 4 disposed just below the objective lens 8 so as to be airtight and slidable by a sealing material 13 such as an O-ring. . The support member 12, that is, the target 10 is movable between the center axis α position of the electron gun 5 indicated by the solid line position in FIG. 2, that is, between the use position and the non-use position indicated by the two-dot chain line. The movement of the support member 12 is performed by the operation member 14. A hole 4 b concentric with the central axis α of the electron gun 5 is formed in the horizontal floor 4 a, and a hole 12 a concentric with the hole 4 b is formed in the support part of the support member 12.
[0019]
When the support member 12, that is, the target 10 is set to the use position indicated by the solid line in FIG. 2, the inside of the casing 4 of the electron microscope 2 is hermetically cut off by the electron beam generator A side and the sample 9 side B, and When the support member 12, that is, the target 10 is set at the non-use position indicated by the two-dot chain line in FIG. 2, the inside of the casing 4 of the electron microscope 2 communicates between the electron beam generation unit side A and the sample 9 side B. It is like that. That is, the support member 12 of the target 10 also serves as a gate valve that shuts off the electron beam generation unit side A and the sample 9 side B in an airtight manner. Thereby, the sample 9 side can be made into the atmosphere or helium atmosphere while the electron beam generating part A side is kept in a high vacuum.
[0020]
Further, the focal point of the electron beam is tied on the surface of the sample 9 when the target 10 is set at the non-use position, and on the surface of the target 10 when the target 10 is set at the use position. Are controlled to be switched. This focus switching is performed in conjunction with the movement of the target 10. In the analytical electron microscope 1 of this example, since the electron beam is set to focus on the target 10, the target 10 is not illustrated in order to prevent damage due to heat generated by electron beam irradiation. It is cooled by the cooling means.
[0021]
In the analytical electron microscope 1 of this example configured as described above, when the target 10 is set at the use position, that is, when inserted between the objective lens 8 and the sample 9, the fluorescent X-ray analyzer mode is set. When set and the target 10 is removed from between these, the scanning electron microscope mode is set.
[0022]
When the fluorescent X-ray analyzer mode is set, the electron beam emitted from the electron gun 5 is accelerated to focus on the target 10. At this time, the electron beam irradiates the target 10. Thus, X-rays are generated from the target 10, and the X-rays pass through the metal thin film target 10 to irradiate the sample 9. Thereby, fluorescent X-rays are generated from the sample 9, and the generated fluorescent X-rays are detected by the X-ray detector 3 and analyzed by the X-ray analyzer as in the conventional case.
[0023]
On the other hand, when the scanning electron microscope mode is set, the electron beam emitted from the electron gun 5 is accelerated to focus on the sample 9, and the sample 9 is scanned by the same scanning electron microscope as in the conventional case. Analysis is performed.
[0024]
According to the analytical electron microscope 1 of this example, the sample 9 is irradiated with the electron beam from the electron gun 5 being focused on the surface of the sample 9 with the target 10 removed from the support member 12. Thus, the same function of the conventional scanning electron microscope 2 can be achieved, and the electron beam from the electron gun 5 is focused on the surface of the target 10 while the target 10 is supported by the support member 12. By irradiating the target 10 so as to tie, the function of the fluorescent X-ray analyzer similar to the conventional one that measures the minute part of the sample 9 can be exhibited. That is, the analytical electron microscope 1 of this example is a device that has both the function of the scanning electron microscope 2 and the function of the fluorescent X-ray analyzer, and is optimal by switching these two functions depending on the analysis object and purpose. Analysis under conditions is possible.
[0025]
In addition, simply by installing the target 10 and the collimator 11 on the conventional scanning electron microscope 2, the analytical electron microscope 1 having the two functions described above can be configured easily and inexpensively.
[0026]
Furthermore, by incorporating the target 10 and the collimator 11 into the scanning electron microscope 2, a high-intensity micro focus with X-rays can be easily obtained. Therefore, since the X-ray beam generated from the target 10 becomes very thin, the use efficiency of X-rays is extremely higher than that of the X-ray tube in the conventional X-ray fluorescence analyzer, and a highly sensitive analysis can be performed. It becomes like this.
[0027]
Although not shown, a filter for improving the monochromaticity of the irradiated X-ray and blocking the electron beam may be provided between the target 10 and the sample 9.
[0028]
FIG. 3 is a view similar to FIG. 1, showing another example of the embodiment of the present invention. The same components as those in the above-described example are denoted by the same reference numerals, and detailed description thereof is omitted.
[0029]
In the above example, the target 10 is arranged between the objective lens 8 of the scanning electron microscope 2 and the sample 9, but in the analysis microscope 1 of this example, as shown in FIG. A type analytical electron microscope 2 'is used, and a metal thin film target 10 is placed at an intermediate image point between the condenser lens 7 and the objective lens 8 of the scanning analytical electron microscope 2' in the same manner as described above. It is provided to be movable.
Other configurations of the analytical electron microscope 1 in this example are the same as those in the above-described example.
[0030]
In the analysis electron microscope 1 of this example configured as described above, when the target 10 is inserted at an intermediate image point between the condenser lens 7 and the objective lens 8, that is, at the use position, the electron beam is applied to the target 10. The target 10 emits X-rays, and the sample 9 is irradiated with the X-rays to set the fluorescent X-ray analyzer mode for analyzing the fluorescent X-rays generated from the sample 9. When the imaging point is removed, that is, when it is set at a non-use position, the electron beam is irradiated so as to focus on the sample 9, thereby scanning characteristic X-rays generated from the sample 9. The electron microscope mode is set.
[0031]
In that case, since the target 10 is inserted at an intermediate image point between the condenser lens 7 and the objective lens 8, the target 10 is inserted between the objective lens 8 and the sample 9 as in the above-described example. In comparison, the working distance of the scanning analytical electron microscope 2 'is not limited. Thereby, a working distance becomes short and high resolution is obtained in the scanning analysis electron microscope mode of the analysis electron microscope 1.
[0032]
Further, since the target 10 is inserted at the imaging point of the condenser lens 7, it is not necessary to change the excitation condition of the objective lens 8 in the fluorescent X-ray analyzer mode and the scanning analysis electron microscope mode. Thereby, operation at the time of switching between both modes becomes easier.
[0033]
Furthermore, when the target 10 is inserted at the imaging point of the condenser lens 7, the electron beam irradiation current can be larger than when the target 10 is inserted below the objective lens 8 as in the above-described example. It becomes like this. Thereby, the generation amount of X-rays in the target 10 increases.
[0034]
【The invention's effect】
As is apparent from the above description, according to the analytical electron microscope of the first aspect of the invention, it is possible to configure an apparatus that combines the function of an electron microscope and the function of a fluorescent X-ray analyzer with a single unit. Therefore, it is possible to perform analysis under the optimum conditions by appropriately switching these two functions depending on the analysis object and purpose.
Moreover, an analytical electron microscope having two functions can be easily and inexpensively configured simply by installing a target on a conventional electron microscope.
[0035]
In addition, since the electron beam generating unit side and the sample side are hermetically blocked by the target support member, the sample side is kept in the atmosphere or helium atmosphere while the electron beam generating unit side is kept at a high vacuum. It becomes possible.
[0036]
Further, according to the invention of claim 2, since the X-rays irradiating the sample are limited by the collimator, it becomes possible to easily obtain a finer focus with higher brightness of the X-rays. Therefore, since the X-ray beam from the target can be made very thin, the utilization efficiency of X-rays can be greatly improved compared to the X-ray tube in the conventional X-ray fluorescence analyzer, and a highly sensitive analysis can be performed. become able to.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an example of an embodiment of an analytical electron microscope according to the present invention.
FIG. 2 is a detailed enlarged view of a portion II in FIG.
FIG. 3 is a diagram schematically showing another example of the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Analysis electron microscope, 2 ... Scanning electron microscope, 3 ... X-ray detector, 4 ... Casing, 5 ... Electron gun, 6 ... Anode, 7 ... Condenser lens, 8 ... Objective lens, 9 ... Sample, 10 ... Target , 11 ... collimator, 12 ... support member, 13 ... seal member

Claims (2)

In the casing, an electron gun that emits an electron beam, a lens that converges the electron beam, and a sample support unit that is disposed on the central axis of the electron gun below the lens and supports the sample. And an electron microscope equipped with an X-ray detector for detecting X-rays generated from the sample in the casing,
A target is disposed between the lens and the sample support portion so as to be movable between a use position on the central axis and a non-use position deviating from the central axis.
When the target is set at the use position, the electron beam is focused on the surface of the target, so that X-rays generated from the target irradiate the sample, and fluorescent X-rays generated from the sample X-ray fluorescence analyzer mode for detecting the X-ray by the X-ray detector, and when the target is set at the non-use position, the electron beam is focused on the surface of the sample and generated from this sample. An electron microscope mode for detecting characteristic X-rays to be detected by the X-ray detector is set.
The target is hermetically fixed and supported by a support member movably provided on the casing, and the target and the support member are arranged on the electron beam generator side and the sample when the target is positioned at a use position. isolation from the side airtightly and analytical electron microscope, wherein the benzalkonium through communication between the electron beam generating section side and the sample side when brought into position the target at the non-use position.   The analytical electron microscope according to claim 1, wherein a collimator for limiting X-rays is disposed on the central axis line closer to the sample support part than the use position of the target.

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